migrate net ip field from blob to json

management/server/migration/migration.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"net"
 	"strings"
 
 	log "github.com/sirupsen/logrus"
@@ -99,3 +100,96 @@ func MigrateFieldFromGobToJSON[T any, S any](db *gorm.DB, fieldName string) erro
 
 	return nil
 }
+
+// MigrateNetIPFieldFromBlobToJSON migrates a Net IP column from Blob encoding to JSON encoding.
+// T is the type of the model that contains the field to be migrated.
+// S is the type of the field to be migrated.
+func MigrateNetIPFieldFromBlobToJSON[T any](db *gorm.DB, fieldName string, indexName string) error {
+	oldColumnName := fieldName
+	newColumnName := fieldName + "_tmp"
+
+	var model T
+
+	if !db.Migrator().HasTable(&model) {
+		log.Printf("Table for %T does not exist, no migration needed", model)
+		return nil
+	}
+
+	stmt := &gorm.Statement{DB: db}
+	err := stmt.Parse(&model)
+	if err != nil {
+		return fmt.Errorf("parse model: %w", err)
+	}
+	tableName := stmt.Schema.Table
+
+	var item string
+	if err := db.Model(&model).Select(oldColumnName).First(&item).Error; err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			log.Printf("No records in table %s, no migration needed", tableName)
+			return nil
+		}
+		return fmt.Errorf("fetch first record: %w", err)
+	}
+	if len(item) < 0 {
+		return fmt.Errorf("no records fetched")
+	}
+
+	var js json.RawMessage
+	var syntaxError *json.SyntaxError
+	err = json.Unmarshal([]byte(item), &js)
+	if err == nil || !errors.As(err, &syntaxError) {
+		log.Debugf("No migration needed for %s, %s", tableName, fieldName)
+		return nil
+	}
+
+	if err := db.Transaction(func(tx *gorm.DB) error {
+		if err := tx.Exec(fmt.Sprintf("ALTER TABLE %s ADD COLUMN %s TEXT", tableName, newColumnName)).Error; err != nil {
+			return fmt.Errorf("add column %s: %w", newColumnName, err)
+		}
+
+		var rows []map[string]any
+		if err := tx.Table(tableName).Select("id", oldColumnName).Find(&rows).Error; err != nil {
+			if errors.Is(err, gorm.ErrRecordNotFound) {
+				log.Printf("No records in table %s, no migration needed", tableName)
+				return nil
+			}
+			return fmt.Errorf("find rows: %w", err)
+		}
+
+		for _, row := range rows {
+			blob, ok := row[oldColumnName].(string)
+			if !ok {
+				return fmt.Errorf("type assertion failed")
+			}
+
+			jsonValue, err := json.Marshal(net.IP(blob))
+			if err != nil {
+				return fmt.Errorf("re-encode to JSON: %w", err)
+			}
+
+			if err := tx.Table(tableName).Where("id = ?", row["id"]).Update(newColumnName, jsonValue).Error; err != nil {
+				return fmt.Errorf("update row: %w", err)
+			}
+		}
+
+		if indexName != "" {
+			if err := tx.Migrator().DropIndex(&model, indexName); err != nil {
+				return fmt.Errorf("drop index %s: %w", indexName, err)
+			}
+		}
+
+		if err := tx.Exec(fmt.Sprintf("ALTER TABLE %s DROP COLUMN %s", tableName, oldColumnName)).Error; err != nil {
+			return fmt.Errorf("drop column %s: %w", oldColumnName, err)
+		}
+		if err := tx.Exec(fmt.Sprintf("ALTER TABLE %s RENAME COLUMN %s TO %s", tableName, newColumnName, oldColumnName)).Error; err != nil {
+			return fmt.Errorf("rename column %s to %s: %w", newColumnName, oldColumnName, err)
+		}
+		return nil
+	}); err != nil {
+		return err
+	}
+
+	log.Printf("Migration of %s.%s from blob to json completed", tableName, fieldName)
+
+	return nil
+}